I have a DSL 675K.. something close to that and my connection i getting out of whack.. I've just reformatted and install a fresh win7 so there's no chances of spyware, malware, viruses could be the causes of this issues.. Anybody here has any clue what's going on? P.S. Just a couple of weeks ago my internet works flawless.
Well if you tried installing Windows again, it clearly is not a software problem, it could be a hardware fault, or your ISP and decided to cut you off or something. Try contacting them as suggested above.
I think your system is slow due to registry files. Install or uninstall program can make your registry confusion that is harmful and slow your system. You have to use registry easy...
Also i would recommend checking your router or if you have a wireless network hub or it can be a wireless ethinet board on your computer that is the problem. I had a problem similar to yours which was a filter connection that was fault. There can be many issues which caused the problem from say hardware , software , to external problems ISP fault etc. Hope all get fixed soon.